Method for polishing workpiece, polishing apparatus and method for manufacturing semiconductor device

ABSTRACT

A region free of groove is provided in a central portion of a polishing pad, and a region having grooves formed thereon is provided on the outer portion thereof. A retainer ring surrounds and sustains a circumference portion of the wafer, and a part that tends to provide higher polishing rate, which is adjacent to the retainer ring in the circumference portion, is disposed so as to face against the region free of the groove. Then, while pressing the wafer against the polishing pad, these are rotated in the same direction. Then, a slurry is supplied from a slurry feeding unit to the outer portion of the region free of groove. Since substantially no slurry is supplied in the region free of groove, the polishing rate is reduced there, and thus a uniform polishing rate over the entire wafer is provided.

The present application is based on Japanese Patent Application NO.2003-419532, the whole disclosure of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for polishing a workpiece anda polishing apparatus, and also generally relates a method formanufacturing a semiconductor device.

2. Related Art

When a reflow process, an application process such as a spin on glass(SOG) process, or an etch back process, for example, is conducted forplanarizing a wafer within a process for manufacturing a semiconductordevice including a wafer composed of silicon or the like, it isdifficult to planarize over the wider region of the surface of thewafer. Such difficulty may be a considerable barrier for themanufacturing process for the semiconductor device. In suchcircumstances, a chemical mechanical polishing (CMP) process, whichprovides a polishing of the surface of the wafer by a combination of amechanical action and a chemical action, becomes to be a mainstream ofthe polishing process.

CMP process and polishing apparatus employed for CMP are disclosed inJapanese Patent No. 3,042,593, Japanese Patent Laid-Open No.H08-229,805, Japanese Patent Laid-Open No. 2003-260,657, Japanese PatentNo. 3,324,643, and Japanese Patent No. 3,006,568. In the polishingdevice disclosed in Japanese Patent No. 3,042,593, a polishing pad(abrasive cloth) is put on a rotatable circular table, and a career,which rotates and moves a wafer (workpiece) while sustaining the waferso as to maintain the wafer facing against the polishing pad, isprovided.

The wafer is polished by pressing the wafer against the polishing padwhile rotating the polishing pad and the wafer in the same direction,and further reciprocating and swinging or oscillating the carrier alongthe direction of crossing the rotating direction (for example, radialdirection). More specifically, grooves and/or pores are formed on thepolishing pad composed of polyurethane or the like, and an abrasivematerial (slurry) is supplied to the polishing pad. The slurry istransferred through the grooves to respective portions of the polishingpad and remained within the pores, and the remained slurry is utilizedto polish the entire surface of the wafer. The technology disclosed inJapanese Patent No. 3,042,593 comprises the grooves on the polishing padthat are useful in preventing a phenomenon of the wafer sticking on thepad, which is caused by a negative pressure generated therein under thecondition of the wafer being closely contacted onto the polishing pad.In addition, sufficient strength of the polishing pad is ensured byadjusting the interval (density) of the grooves and the interval(density) of the pores.

A polishing pad disclosed in Japanese Patent Laid-Open No. H08-229,805is also available to be employed in a polishing apparatus, which issubstantially similar to that disclosed in Japanese Patent No.3,042,593. Further, the polishing pad of Japanese Patent Laid-Open No.H08-229,805 comprises independent two regions, which includes a regionwhere grooves for allowing the transfer of the slurry therethrough areformed, and a region where pores for maintaining the slurry therein areformed. More specifically, the regions having grooves formed therein aredisposed in an inner portion and a circumference portion of thepolishing pad, and another region containing pores formed therein isalso disposed between the inner portion and the outer circumferenceportion. In this case, no pore is formed in the region where the groovesare formed, and no groove is formed in the region where the pores areformed. Polishing at higher polishing rate can be achieved at the regionwhere the pores are formed, compared with the region where grooves areformed. This is because the slurry contained within the pores as ifbeing fixed therein provides more compressive polishing of the surfaceof the wafer than the slurry freely transferring through the grooves.Uniform conditions for polishing the entire wafer can be achieved bypolishing the central portion of the wafer that provides shorter movingdistance in a unit angular movement of the rotation thereof at a higherpolishing rate with the region of the pad where pores are formed, in thetechnology disclosed in Japanese Patent Laid-Open No. H08-229,805.

In addition, the second example disclosed in Japanese Patent Laid-OpenNo. H08-229,805 includes a configuration, in which a region having poresformed therein at lower density is disposed in the inner portion and theouter circumference portion of the polishing pad, and a region havingpores formed therein at higher density is disposed between the innerportion and the outer circumference portion. Since the region havingpores formed therein at higher density is capable of maintaining moreslurry than the region having pores formed therein at lower density, theregion having pores at higher density can provide the polishing athigher polishing rate. Therefore, similarly as in the aforementionedconfiguration, uniform polishing condition can be achieved.

Japanese Patent Laid-Open No. 2003-260,657 discloses a configuration inFIG. 1 to FIG. 4, in which widths of concave portions of grooves fortransferring the slurry formed on the principal surface of the polishingpad are not constant. In this configuration, the concave portions in thegrooves in the inner side of the polishing pad are formed to havenarrower widths and the concave portions in the grooves in thecircumference side are formed to have wider widths, so that the amountof the slurry fed into the polishing pad is provided as uniformlypossible over the entire polishing pad.

SUMMARY OF THE INVENTION

We have now discovered the following. FIG. 15A is a schematic side viewof a conventional polishing apparatus, showing the configurationthereof. As shown in FIG. 15A, a carrier sustaining thereon a wafer 101to be polished typically comprises a retainer ring 102 a surrounding acircumference portion of the wafer 101 for sustaining the wafer 101 withhigher reliability.

The retainer ring 102 a is often in contact with a surface of apolishing pad 103 when the wafer 101 is polished by providing acompressible contact with the polishing pad 103, in which the slurry 108is supplied. Since the wafer 101 and the polishing pad 103 rotate and/oroscillate in the condition that the retainer ring 102 a is incompressible contact with the polishing pad 103 of a thin cloth in suchoccasion, the polishing pad 103 is in a condition of floating itself (orbouncing) in a periphery of a position where the retainer ring 102 amakes a compressible contact, as shown in FIG. 15B. Since the polishingpad 103 is compressed against the wafer 101, which is shown by thetwo-dot chain line in the figure, the pressure generated by thecompressible contact between the wafer 101 and the polishing pad 103tends to be increased in the periphery of the retainer ring 102 a ornamely in the circumference portion of the wafer 101, even though thepolishing pad 103 actually does not extremely distorted as shown by theexaggerated diagram in FIG. 15B. As a result, the polishing rate ishigher in the circumference portion compared with the central portion ofthe wafer 101, as shown in FIG. 16. For example, in the case of thewafer 101 having a diameter of about 200 mm, the polishing rate ishigher by 10 to 15% in a toroidal region having a width of about 10 mmfrom the circumference edge of the wafer than in the central portionthereof. More specifically, when the polishing rate in the centralportion thereof is 200 nm/min, the polishing rate in the circumferenceportion may be 220 to 230 nm/min.

Although the technology disclosed in Japanese Patent No. 3,042,593allows uniformly increasing and decreasing the polishing rate for theentire wafer, it may be difficult to prevent to generate a region forpresenting higher polishing rate and a region for presenting lowerpolishing rate within the wafer, thereby providing uneven surfacecondition of the wafer, as shown in FIG. 15B and FIG. 16.

On the other hand, the technology disclosed in Japanese Patent Laid-OpenNo. H08-229,805 provides a region where higher polishing rate isobtained than other region in the polishing pad (region where pores areformed or perforated region), and thus polishing the wafer by utilizingsuch region of the pad provides uniform polishing rate across thesurface of the wafer and, in turn, provides uniform surface condition ofthe polished wafer.

Nevertheless, the configuration disclosed in Japanese Patent Laid-OpenNo. H08-229, 805 requires to form a new type of a polishing pad, whichis totally different from the conventionally employed (for example,commercially available) polishing pad. Moreover, the manufacture of suchnew type of polishing pad is complicated, and the manufacturing cost maybe high. More specifically, a process for forming grooves including, forexample, a process for rotating the polishing pad while a tool having ablade shape is pressed against the polishing pad, and a process forforming pores including, for example, a process for stinging aneedle-shape tool into the polishing pad, are necessary to be carriedout for manufacturing each piece of the polishing pad. As such, at leasttwo different operations must be conducted for forming the grooves andthe pores in one piece of the polishing pad.

Since the size of the region where pores are formed is determinedaccording to the size of the wafer, the configuration may not possiblybe generally adopted for polishing the wafers having different sizes.This problem will be further described as follows.

In the first place, it can be considered that Japanese Patent Laid-OpenNo. H08-229, 805 is presented by recognizing the tendency of thepolishing rate, which is reduced due to the narrower moving rangethereof in vicinity of the center of the wafer. However, another type ofproblem that is not related to Japanese Patent Laid-Open No. H08-229,805is arisen, where the polishing rate is increased as the polishing pad isto be distorted at the periphery of the retainer ring that is caused bythe compressive contacts with the retainer ring in the circumferenceportion of the wafer. (see FIG. 15B and FIG. 16). The problem is atendency, in which, as described above, higher polishing rate isobtained in a toroidal region having a width of about 10 mm from thecircumference edge of the wafer (in other words, circumference portion)and lower polishing rate is obtained in other region (that is, centralportion).

When the configuration of Japanese Patent Laid-Open No. H08-229,805 isapplied thereto to polish the central portion of the wafer (in otherwords, portions except the toroidal region having width of about 10 mmfrom the circumference edge) with the region of the polishing pad havingpores formed therein, it may be considered that uniform polishingcondition can be achieved. In such case, since the range on the surfaceof the wafer to be polished with the region of the polishing pad havingpores formed therein is different between the case of polishing a waferhaving smaller diameter and the case of polishing a wafer having largerdiameter, it is naturally desired that the geometry of the region of thepolishing pad having pores should be suitably selected. Specificallydescribing thereof in simple examples: when a wafer 104 having adiameter of 200 mm is polished as shown in FIG. 17A, a portion 104 a ofa diameter of about 180 mm should be polished with a region 105 a of thepolishing pad 105 having pores formed therein, and when a wafer 106having a diameter of 300 mm is polished as shown in FIG. 17B, a portion106 a of a diameter of about 280 mm should be polished with a region 107a of the polishing pad 107 having pores formed therein. Therefore, it isdesired that the sizes of the regions 105 a and 107 a both having poresformed therein should be suitably selected corresponding to the sizes ofthe wafer 104 and the wafer 106, as shown in FIG. 17A and FIG. 17B,respectively. It is considered that this is because the phenomenon ofcausing the floating (or bouncing) of the polishing pad 103 in aperiphery of the retainer ring 102 a occurs within a certain rangethereof regardless of the size of the wafer, as shown in FIG. 15B.

Here, it is assumed that the oscillating ranges of the wafer 104 and thewafer 106 are almost fixed in the cases of FIG. 17A and FIG. 17B,respectively. It can also be expected that a polishing pad 107 includingsmaller region 107 a having pores formed therein can be available forpolishing the larger wafer 106 by increasing the oscillating rangethereof. However, in such case, the oscillating ranges should beconsiderably changed on a case-by-case base according to the sizes ofthe wafer 104 and the wafer 106, and thus complicated apparatusstructure and complicated polishing process are required, and the wholesize of the polishing apparatus and the manufacturing cost may beincreased.

As such, when the configuration of Japanese Patent Laid-Open No.H08-229,805 is applied thereto to solve the problem of difficulty inobtaining uniform polishing rates as shown in FIG. 15A, FIG. 15B andFIG. 16 without further consideration, it is difficult to be generallyadapted to different wafer sizes by utilizing a single polishing pad.Therefore, the respective polishing pads containing the region havingpores formed therein, which have appropriate sizes that meet therespective sizes of the wafers, are necessary to be prepared inrespective cases of polishing wafers of various sizes. According toJapanese Patent Laid-Open No. H08-229,805, the polishing pads havingnovel configuration that has not been presented in the conventionaltechnology should be tailored to comply with the different wafer sizesin each time of polishing wafers having different sizes, and thus theproduction cost for wafers may be increased.

In addition, the type of the polishing pad including the region havingpores formed therein as disclosed in Japanese Patent Laid-Open No.H08-229,805 may possibly cause a plugging of the pad due to a localdrying-up, and thus there is a possibility to cause a scratch on thepolished wafer.

Uniform feeding quantity of the slurry into the principal surface of thepolishing pad is aimed in the technology disclosed in Japanese PatentLaid-Open No. 2003-260,657. However, inventors of Japanese PatentLaid-Open No. 2003-260,657 does not seem to consider the fact that theportion of the workpiece of wafer for providing higher polishing rateexists as described above. Therefore, even if the amount of thepolishing by the slurry is controlled to be uniform as described inJapanese Patent Laid-Open No. 2003-260,657, it is highly possible toprovide no contribution for achieving uniform polishing conditions ofthe polished wafers. More specifically, the technology described inJapanese Patent Laid-Open No. 2003-260,657 is made by only consideringon how the quantity of the slurry feed is controlled, and thus thetechnology described in Japanese Patent Laid-Open No. 2003-260,657,which does not focus on the tendency of the polishing rate of theworkpiece of the wafer, is not always effective in the real polishingoperation.

Therefore, the present invention is made on the basis of particularlyfocusing on the fact that the polishing rate of the circumferenceportion of the workpiece such as wafer sustained on the ring-typeretainer such as retainer ring is higher, and the present inventionprovides a technology of presenting a uniform polishing rate over theworkpiece in a real polishing operation to provide a uniform surfacecondition over the workpiece.

According to one aspect of the present invention, there is provided amethod for polishing a workpiece, comprising: providing a compressiblecontact between a principal surface of a polishing pad and a polishingsurface of a workpiece; continuously moving a relative position of thepolishing pad with the workpiece while the condition of being incompressible contact between the principal surface of the polishing padand the polishing surface of the workpiece is maintained; and supplyingan abrasive material between the polishing pad and the workpiece,wherein quantity of the abrasive material contacting the workpiece has adistribution profile over a region where the principal surface of thepolishing pad is in contact with the polishing surface of the workpiece.The abrasive material has the distribution profile over the polishingpad.

Here, “the region where the principal surface of the polishing pad andthe polishing surface of the workpiece are in contact” utilized in thepresent invention indicates a region in the principal surface of thepolishing pad, on, over or above which the workpiece can be disposed,and these may be directly contacted or an abrasive material may bedisposed therebetween, provided that the principal surface of thepolishing pad faces against the polishing surface of the workpiece.

In the present invention, the workpiece may be exemplified bysemiconductor wafer and glass substrate, which may include predetermineddevices thereon.

According to the present invention, since the abrasive material issupplied so that the quantity of the abrasive material contacting theworkpiece has a distribution profile in a region where a principalsurface of the polishing pad and a polishing surface of the workpieceare in contact, the polishing rate is reduced in the region ofcontaining smaller amount of the abrasive material that contacts theworkpiece, and thus the polishing rate can be suitably controlled withinthe polishing surface of the workpiece by utilizing such distributionprofile of the quantity of the abrasive material. Therefore, uniformpolishing rate can be obtained in a simple process with lower cost.

The aspect of the present invention may further comprise an additionalconfiguration, in which the aforementioned process of supplying theabrasive material may include supplying the aforementioned region sothat the quantity of the abrasive material supplied within a unit areaof the aforementioned principal surface in a unit time is not uniformacross the aforementioned region.

The aspect of the present invention may further comprise an additionalconfiguration, in which the shape of the aforementioned principalsurface of the polishing pad is a circle, and the aforementioned processof supplying the abrasive material may include supplying theaforementioned abrasive material so that the quantity of the abrasivematerial supplied within a unit area of the aforementioned principalsurface in a unit time varies at any position along the direction of theradius of the polishing pad to form a distribution profile thereof.

The aspect of the present invention may further comprise an additionalconfiguration, in which the polishing pad is rotated around a centralaxis, and the workpiece is oscillated on a region where the abrasivematerial has a distribution profile. Having such configuration, uniformpolishing rate can more definitely be achieved.

The aspect of the present invention may further comprise an additionalconfiguration, in which quantity of the abrasive material is lower in alocation that is closer to the center than a position where the abrasivematerial is dropped, and quantity of the abrasive material is higher ina location that is closer to the outer circumference than the position.This may be effective since the polishing pad rotates during thepolishing process to generate a centrifugal force, which, in turn,substantially prevents the abrasive material moving toward the centerfrom the dropping position of the abrasive material.

The aspect of the present invention may further comprise an additionalconfiguration, in which the polishing pad is provided with groovesformed thereon, and wherein, on the polishing pad, quantity of theabrasive material is lower in a region where density of the grooves islower, and quantity of the abrasive material is higher in a region wheredensity of the grooves is higher. This may be effective since the amountof the abrasive material transferred to the region having lower densityof the grooves is smaller. Here, the density of the grooves appeared inthis specification indicates areas of regions occupied by the groovesper unit area of the polishing pad, viewing from a normal line directionof the principal surface of the polishing pad.

The aspect of the present invention may further comprise an additionalconfiguration, in which density of the grooves is lower in a centralregion of the polishing pad, and density of the grooves is higher in acircumference region thereof. In addition, the central region of thepolishing pad may be free of the groove. Having such configuration, thedistribution profiles of the quantity of slurry feed are definitelypresented in the central region and the circumference region of thepolishing pad. Therefore, the polishing rate can more definitely becontrolled over the polishing surface.

The aspect of the present invention may further comprise an additionalconfiguration, in which the polishing pad is provided with groovesformed therein, and wherein, on the polishing pad, quantity of theabrasive material is lower in a region where a width of a concaveportion in the groove is narrower, and quantity of the abrasive materialis higher in a region where a width of a concave portion in the grooveis wider. The width of the concave portion in the groove may be narrowerin the central region of polishing pad, and the width of the concaveportion in the groove may be wider in the circumference region of thepolishing pad.

The aspect of the present invention may further comprise an additionalprocess of providing a compressible contact between a principal surfaceof the polishing pad and a polishing surface of the workpiece, so thatat least a portion on the polishing surface of the workpiece, whichtends to provide higher polishing rate, is located in a region on theprincipal surface of the polishing pad, which contains less quantity ofthe abrasive material. Having such additional process, more uniformpolishing rate can be stably achieved. More specifically, the presentinvention is not intended to simply providing uniform feeding of theabrasive material, but allows providing uniform polishing rate in thereal polishing process by providing a distribution profile of the feedquantity of the abrasive material in consideration of the tendency ofthe polishing rate for the workpiece.

The aspect of the present invention may further comprise an additionalprocess of: acquiring a tendency of a distribution profile of thepolishing rate in the aforementioned polishing surface of the workpiece;and determining a region of the workpiece located over the polishing padbased on the acquired tendency, wherein the aforementioned process forcontinuously moving the relative position of the polishing pad and theworkpiece can be conducted within the determined region. Having suchadditional process, the tendency of the distribution profile of thepolishing rate can be acquired using a dummy workpiece in advance, andthus the variation of the polishing rates for products within thepolishing surface of the workpiece can definitely be prevented.

The aspect of the present invention may further comprise an additionalconfiguration, in which a ring-type retainer surrounds a circumferenceportion of the workpiece to sustain the workpiece, and wherein theportion on the polishing surface of the workpiece, which tends toprovide higher polishing rate, is a portion of the circumference portionbeing adjacent to the ring-type retainer.

According to another aspect of the present invention, there is provideda method of polishing a workpiece, comprising: providing a compressiblecontact between a principal surface of a polishing pad and a polishingsurface of a workpiece; continuously moving a relative position of thepolishing pad against the workpiece while the condition of being incompressible contact between the principal surface of the polishing padand the polishing surface of the workpiece is maintained; and supplyingan abrasive material between the polishing pad and the workpiece,wherein a circumference portion of the workpiece is sustained with aring-type retainer, and wherein a portion of the ring-type retainerforces the polishing pad and the workpiece so that the polishing pad isin compressible contact with the workpiece, while the ring-type retaineris disposed so that at least a portion of the ring-type retainer extendsbeyond an edge of the polishing pad. Since this configuration includesdisposing the ring-type retainer so that at least a portion of thering-type retainer extend beyond the polishing pad, the distortion ofthe polishing pad caused by the compressible contact of the ring-typeretainer against the polishing pad can be reduced. Therefore, theincrease of the polishing rate in that portion can be inhibited.

According to further aspect of the present invention, there is provideda polishing pad for polishing a workpiece by forcing a rotatingworkpiece to provide a compressible contact between the workpiece andthe polishing pad and by supplying abrasive material between theworkpiece and the polishing pad while the polishing pad being rotated,wherein the polishing pad is partially provided with grooves formedtherein, and wherein density of the grooves has a distribution profileacross a principal surface of the polishing pad, thereby the polishingpad being provided with a first region having lower polishing rate and asecond region having higher polishing rate.

Since the density of the grooves is not uniformly distributed over thesurface of the polishing pad according to the aspect of the presentinvention, the polishing rate can be uniformly distributed over thesurface corresponding to the non-uniformity of the groove density, evenif the polishing rate for the workpiece has not been uniformlydistributed over the polishing surface.

The aspect of the present invention may further comprise an additionalconfiguration, in which the density of the groove on the polishing padis lower in a region of the polishing pad corresponding to higherpolishing rate portion of the workpiece and the density of the groove onthe polishing pad is higher in a region of the polishing padcorresponding to lower polishing rate portion of the workpiece. Theaspect of the present invention may further comprise an additionalconfiguration, in which a width of a concave portion in the groove ofthe polishing pad is narrower in a region of the polishing padcorresponding to higher polishing rate portion of the workpiece and awidth of a concave portion in the groove of the polishing pad is widerin a region of the polishing pad corresponding to lower polishing rateportion of the workpiece. The configuration of the present invention mayfurther comprise an additional feature, in which the density of thegrooves is lower in a central region of the polishing pad, or the widthof the concave portion in the groove is narrower in a central region ofthe polishing pad. Alternatively, the aspect of the present inventionmay further comprise an additional configuration, in which the centralregion of the polishing pad is free of the groove.

The aspect of the present invention may further comprise an additionalconfiguration, in which the grooves are concentric circular.

According to yet other aspect of the present invention, there isprovided a polishing apparatus, comprising a polishing pad having anyone of the aforementioned configurations. According to the polishingapparatus of the present invention, the workpiece can be uniformlypolished within polishing surface.

The aspect of the present invention may further comprise an additionalconfiguration, in which the polishing apparatus further comprises: apolishing pad driving unit which rotates the polishing pad; an abrasivematerial feeding unit which supplies an abrasive material to apredetermined position on the polishing pad; and a workpiece drivingunit which rotates the workpiece while forcing the workpiece so that theworkpiece is in compressible contact with the polishing pad.

The aspect of the present invention may further comprise an additionalconfiguration, in which the polishing pad driving unit and the workpiecedriving unit comprise a mechanism for providing a compressible contactbetween a principal surface of the polishing pad and a polishing surfaceof the workpiece so that at least a portion of the polishing surface ofthe workpiece having tendency to provide higher polishing rate islocated in a region containing smaller amount of the abrasive materialof a principal surface of the polishing pad. Having such configuration,the variation of the polishing rate can be definitely inhibited.

The aspect of the present invention may further comprise an additionalconfiguration, in which the workpiece driving unit comprises a ring-typeretainer for surrounding a circumference portion of the workpiece tosustain the workpiece, and wherein the portion of the polishing surfaceof the workpiece having tendency to provide higher polishing rate is aportion of a circumference portion being adjacent to the ring-typeretainer.

According to yet further aspect of the present invention, there isprovided a polishing apparatus, comprising: a polishing pad; a polishingpad driving unit which rotates the polishing pad; and a workpiecedriving unit which forces the workpiece so that the workpiececompressibly contacts the polishing pad while rotating the workpiece,the workpiece driving unit comprising a ring-type retainer forsurrounding a circumference portion of the workpiece to sustain theworkpiece, and the workpiece driving unit being capable of sustainingthe workpiece thereon so that at least a portion of the ring-typeretainer extends beyond an edge of the polishing pad.

According to the configuration described above, since the workpiecedriving unit sustains the workpiece so that at least a portion of thering-type retainer extend beyond the polishing pad, the distortion ofthe polishing pad caused by the compressible contact of the ring-typeretainer against the polishing pad can be reduced. Therefore, theincrease of the polishing rate in the portion can be inhibited.

According to yet other aspect of the present invention, there isprovided a method for manufacturing a semiconductor device, comprising:creating a conducting region within a wafer by utilizing an ionimplantation technology; forming an insulating layer and/or a conductinglayer by utilizing a deposition technology, both of the layers composinga portion of the wafer; processing the wafer into a predetermined shapeby utilizing a lithography technology; and recognizing the wafer as aworkpiece and conducting any one of the aforementioned methods forpolishing the workpiece.

According to yet further aspect of the present invention, there isprovided a method for manufacturing a semiconductor device, comprising:forming an insulating film on a semiconductor substrate; and polishing asurface of the insulating film to planarize the surface of theinsulating film, wherein the polishing is conducted by utilizing any oneof the aforementioned methods for polishing the workpiece.

According to yet other aspect of the present invention, there isprovided a method for manufacturing a semiconductor device, comprising:forming an insulating film on a semiconductor substrate; forming agroove on the insulating film; forming a conducting film within thegroove and on the insulating film; and polishing at least a portion ofthe conducting film formed on the insulating film to planarizing asurface composed of the surface of the insulating film and the surfaceof the conducting film, wherein the polishing is conducted by utilizingany one of the aforementioned methods for polishing the workpiece.

According to these methods for manufacturing semiconductor devices,planarization process for the wafer can be conducted with higherreliability, and thus the resultant semiconductor devices having desiredperformances can be manufactured with higher accuracy.

Although the workpiece often includes a portion that tends to partiallyprovide higher polishing rate, the present invention appropriatelyreduces the polishing rate in such portion, thereby providing uniformpolishing rate over the entire workpiece. This, in turn, allowsproviding higher flatness of the workpiece. Moreover, there is a slimchance to increase the manufacturing cost and to provide complicatedpolishing apparatus and polishing process.

In particular, when the workpiece is sustained on the ring-typeretainer, an increase of the polishing rate in the location in vicinityof the ring-type retainer can be effectively inhibited.

Eventually, the polishing method according to the present invention canbe employed to manufacture the semiconductor device having desiredcharacteristics in a simple and accurate manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1A is a schematic side-view of a polishing apparatus of the firstembodiment of the present invention;

FIG. 1B is a plan view of a polishing pad of the polishing apparatus ofthe first embodiment, showing the configuration thereof;

FIG. 2 is a flow chart, showing the polishing method of the firstembodiment according to the present invention;

FIG. 3 is a graph showing the relationship of the position of the waferwith a polishing rate according to the first embodiment of the presentinvention;

FIG. 4 is a plan view of the polishing pad of the polishing apparatus ofthe second embodiment according to the present invention, showing theconfiguration thereof;

FIG. 5 is a plan view of the polishing pad of the polishing apparatus ofthe third embodiment according to the present invention, showing theconfiguration thereof;

FIG. 6 is a plan view of the polishing pad of the polishing apparatus ofthe fourth embodiment according to the present invention, showing theconfiguration thereof;

FIG. 7 is a plan view of the polishing pad of the polishing apparatusaccording to the modified configuration of the first embodiment of thepresent invention;

FIG. 8 is a plan view of the polishing pad of the polishing apparatusaccording to another modified configuration of the first embodiment ofthe present invention;

FIG. 9A is a plan view of the polishing pad of the polishing apparatusaccording to further modified configuration of the first embodiment ofthe present invention;

FIG. 9B is a cross-sectional view of the polishing pad of FIG. 9A,showing the configuration thereof;

FIG. 10A is a schematic side view of the polishing apparatus of thefifth embodiment according to the present invention, showing theconfiguration thereof;

FIG. 10B is a plan view of the polishing pad of the polishing apparatusof the fifth embodiment according to the present invention, showing theconfiguration thereof;

FIG. 11 is a schematic enlarged side view of the portion of thepolishing apparatus shown in FIG. 10A;

FIG. 12 is a flow chart, showing the polishing method of the fifthembodiment according to the present invention;

FIG. 13A is a schematic cross-sectional view of a semiconductor device,showing a process for manufacturing the semiconductor device accordingto an embodiment of the present invention;

FIG. 13B is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 13C is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 13D is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 13E is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 13F is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 14A is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 14B is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 14C is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 14D is a schematic cross-sectional view of the semiconductordevice, showing the process for manufacturing the semiconductor deviceaccording to the embodiment of the present invention;

FIG. 15A is a schematic side view of a conventional polishing apparatusfor explaining the problem of the conventional polishing apparatus;

FIG. 15B is an enlarged view of a part of the conventional polishingapparatus shown in FIG. 15A for explaining the problem of theconventional polishing apparatus;

FIG. 16 is a graph, showing a relationship of a position of a wafer witha polishing rate within the conventional polishing apparatus shown inFIG. 15A for explaining the problem of the conventional polishingapparatus;

FIG. 17A is a plan view of the polishing pad and a part of the wafer,showing an example of the conventional polishing apparatus suitable forpolishing a smaller wafer for explaining the problem of the prior art;and

FIG. 17B is a plan view of the polishing pad and a part of the wafer,showing an example of the conventional polishing apparatus suitable forpolishing a larger wafer for explaining the problem of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposed.

Preferable embodiments according to the present invention will bedescribed as follows in reference to the annexed figures. In allfigures, identical numeral is assigned to an element commonly appearedin figures, and the detailed description thereof is not presented.

First Embodiment

FIG. 1A and FIG. 1B present schematic diagrams, showing a configurationof a polishing apparatus according to the present embodiment. FIG. 1A isa cross-sectional view of the polishing apparatus. FIG. 1B is a planview, showing a polishing pad 2, a slurry feeder 7, a carrier 4 and awafer 3 sustained on the polishing apparatus shown in FIG. 1A. Thepolishing apparatus shown in FIGS. 1A and 1B will be described. Basicconfiguration of this polishing apparatus is substantially the same asthe conventional apparatus. More specifically, the polishing pad(abrasive cloth) 2 is put on a rotatable table 1, and the carrier 4 formaintaining the wafer (workpiece) 3 is provided so as to face againstthe polishing pad 2. Further, the slurry feeder 7, which is capable ofdropping an abrasive material (slurry) 8 (see FIG. 11) is provided abovethe polishing pad 2. An illustrative example thereof may be that thetable 1 is a circular member having a diameter of about 500 mm, and iscapable of being rotated by a table driving device 5 that isschematically shown here. The combination of the table 1 and the tabledriving device 5 act as a polishing pad driving unit. The carrier 4comprises a retainer ring (ring-type retainer) 4 a surrounding acircumference portion of the wafer 3, a retainer base 4 b sustaining theretainer ring 4 a, a carrier head 4 c pressing down the wafer 3 and aspindle 4 d, which is a rotary drive shaft for the rotation of thesecomponents that are incorporated when rotated. A carrier driving device6, which is capable of integrally rotating and moving the whole of thecarrier 4 and is also capable of pressing against the retainer ring 4 aand the wafer 3 to provide a compressible contact of them with thepolishing pad 2, is coupled to the spindle 4 d. The combination of thecarrier 4 and the carrier driving device 6 act as a workpiece drivingunit. In the present embodiment, the wafer 3 to be polished is acircular wafer having a diameter of about 200 mm.

Next, the polishing pad 2 of the present embodiment will be described inreference to FIG. 1B. The polishing pad 2 is formed of a suitablematerial such as polyurethane or the like, and is a circular memberhaving a diameter of about 500 mm, similarly as the table 1. A polishingsurface (principal surface that contacts the wafer) of the polishing pad2 comprises a region “A” having grooves 2 a formed thereon, and a region“B” being free of groove 2 a. More specifically, the region B having nogroove 2 a formed therein is provided in a rotary central portion of thecircular polishing pad 2 (for example, circular region having a diameterof about 50 mm), and the outer side thereof, the region A having grooves2 a formed thereon is provided. In the present embodiment, the grooves 2a formed in the region A are a plurality of concentric circles, and thedepth is about 0.3 to 1.0 mm.

Polishing process for the wafer 3 by employing the wafer polishingapparatus as shown in FIGS. 1A and 1B will be described in reference tothe flowchart shown in FIG. 2.

First, the retainer ring 4 a surrounds a circumference portion of thewafer 3 to sustain it, and, as described above, the wafer 3 and theretainer ring 4 a are disposed on a predetermined position on thepolishing pad 2 including the region B being free of groove 2 a, namelya region where the slurry 8 is difficult to be supplied, so as toprovide lower polishing rate compared with that of another region A(step S1). More specifically, the wafer 3 and the retainer ring 4 a aresustained so that a portion of the circumference portion (portion thattends to provide higher polishing rate) of wafer 3 faces to the region Bbeing free of groove 2 a, thereby providing a compressible contact withthe polishing pad 2 (step S2). Then, the polishing pad 2 is rotated bythe table 1 and the table driving device 5, and the wafer 3 is rotatedby the carrier 4 and the carrier driving device 6 (step S3).

More specifically, while the retainer ring 4 a and the wafer 3 arepressed against the polishing pad 2 at a pressure of, for example, 0.5to 10.0 psi, a combination of the table 1 and the polishing pad 2 and acombination of the retainer ring 4 a and the wafer 3 are respectivelyrotated in the same direction (for example, anti-clock direction) at aconstant speed of, for example, 20 to 200 rpm (an example may be at 100rpm). In this occasion, the retainer ring 4 a and the wafer 3 arereciprocated and oscillated along the direction of intersecting therotating direction (for example, radial direction) by the carrierdriving device 6. The oscillating range is about 5 to 50 mm (an examplemay be 10 mm), and the period thereof is 5 seconds to 1 minute (anexample may be 10 seconds).

Then, the slurry 8 is dropped onto the polishing pad 2 (step S4). Inthis occasion, a drop port 7 a (see FIG. 1A) of the slurry feeder 7 islocated outside of the region B of the polishing pad 2 having no groove2 a. Therefore, the slurry 8 containing silica, alumina, cerium oxide orthe like is dropped onto the region A having grooves 2 a formed thereon.

As such, as shown in FIG. 1B, the polishing operation is conducted sothat the circumference portion of the wafer 3, that is, the portion thatprovides higher polishing rate around the retainer ring 4 a, asdescribed above (for example, region having a width of about 10 mm fromthe circumference edge), is located in the region B being free of groove2 a of the rotary center portion of the circular polishing pad 2. Theretainer ring 4 a and the wafer 3 are reciprocating and oscillating tocontinue to relatively move the wafer 3 against the polishing pad 2, andit is preferable that the circumference portion of wafer 3 (for example,region having a width of about 10 mm from the circumference edge) is incontact with the region B of free of groove, as described above, astaking an average during the polishing operation.

When the wafer 3 is polished in such manner, the slurry 8 moves throughthe grooves 2 a on the polishing pad 2 and moves from the inner side ofthe surface of the polishing pad 2 toward the outer side thereof by acentrifugal force. The wafer 3 will be polished by the slurry 8.However, the region B being free of groove 2 a is located inner than theslurry dropping position, and since no groove 2 a exists there andfurther the slurry 8 cannot move against centrifugal force, the slurryis never supplied to the region B. Therefore, the region A havinggrooves 2 a formed thereon and the region B being free of groove 2 arespectively have a distribution profile of the quantity of the slurry 8(that is, there are a portion having much amount of the slurry 8 and aportion having with less amount of the slurry 8). Consequently, thepolishing rate of the wafer 3 polished in the region B being free ofgroove 2 a (region containing smaller amount of slurry 8) is lower thanthe polishing rate in the region A having grooves 2 a formed thereon(region containing larger amount of slurry).

Since the circumference portion of the wafer 3 is polished whilemaintaining the condition of contacting with the region B being free ofgroove 2 a as mentioned above in the present embodiment, the polishingrate thereof is lower that that in the central portion of the wafer 3.Since the wafer 3 oscillates while rotating during the polishingprocess, there is no portion that is always polished by the region B offree of groove 2 a, and it periodically comes in contact with the regionB being free of groove 2 a at a frequency of only one time per onerotation of the wafer 3. Nevertheless, after the polishing operation forone wafer 3 for about 30 seconds to 3 minutes is carried out, thepolishing rate of the circumference portion of the wafer 3 adjacent tothe retainer ring 4 a generally reduces to the level equivalent to thepolishing rate of the central portion. This can compensate an increaseof the polishing rate caused by bouncing (floating) of the polishing padshown in FIG. 15B. Eventually, as shown in FIG. 3, the polishing rate ofthe circumference portion can be held down to around ±5% of thepolishing rate of the central portion. For example, the polishing rateof the central portion may be 200 nm/min, and the polishing rate of thecircumference portion may be about 190 to 210 nm/min. In this way,according to the present embodiment, uniform polishing rate over thewafer 3 is provided, and the flatness thereof is improved. Here, thepolishing rate means a rate of polishing of the workpiece per unit time,which is observed when the conditions such as compressible contactingpressure, revolution speed, density of slurry 8 and the like areconstant.

Exemplary usage of the polishing pad of the present embodiment having nogroove in a central portion has been employed in the conventionaltechnology. For example, a polishing pad having no groove in a centralportion and having grooves only in the circumference portion iscommercially available from Rodel Inc., of Phoenix, Ariz. However, theregion of the central portion being free of groove in the conventionaltechnology is intended to only provide a simple handling of thepolishing pad and to simplify the whole manufacturing process, and hasnot been utilized for the polishing process itself. The concept of thetechnology according to the present invention for actively utilizing theregion in the central portion of free of groove in such polishing padfor the polishing operation to achieve an improved control of thepolishing rate, has not existed in the conventional technology.

In other words, according to the present embodiment, uniform surfacecondition of the polished workpiece can be presented for variousdimensions of the workpieces by employing the conventionally existingtypes of the polishing pads. More specifically, the polishing apparatusand the polishing method can be obtained, which provide unexpectedadvantageous effects of providing the uniform polishing rate and theimproved flatness of the wafer without increasing the manufacturing costof the wafer by employing the conventionally utilized polishing pad.

Here, in the present embodiment and the following other embodiments, adummy wafer having the dimension and the material same as that of thecommercial product wafer may be employed to precedently acquireinformation on the level of the variation of the polishing rate when theretainer ring 4 a is employed, and thereafter, the disposing positionfor polishing of a product wafer and the distribution of the feedingquantity the slurry 8 or the distribution of groove density on thepolishing pad 2 may be determined on the basis of the previouslyacquired information, and eventually the wafer 3 may be installed at thepredetermined position to conduct the polishing operation. Thisprocedure can further improve the uniformity of the polishing.

In addition, the workpiece employed in the present embodiment and thefollowing other embodiments is not limited to the semiconductorsubstrates such as a silicon substrate and the like, and may be a glasssubstrate or the like. Further, the polishing apparatus and thepolishing method of the present embodiment and the following otherembodiments may be employed for applications other than polishing thewafer of the semiconductor substrate, such as for polishing opticallens, for example.

Further, the present embodiment is not intended to be limited to theimprovements in the ununiformity of the polishing rate caused by the useof the aforementioned retainer ring 4 a, but is also effective forimproving the ununiformity in the polishing rate caused by any factors,and further, the location of the ununiformity in the polishing rate ofthe workpiece may not be regarded.

The manner of feeding the abrasive material such as slurry 8 or the likeis not limited to the aforementioned configuration of dropping theabrasive material onto the polishing pad, and an alternativeconfiguration of, for example, supplying the abrasive material from aninternal portion of the polishing pad may also be employed.

The present embodiment is advantageous even in the case of employing thepolishing pad that is smaller than the workpiece, and also advantageouseven in conducting the polishing operation by the action of thepolishing pad other than the rotation, such as that the polishing padmoves toward the horizontal direction as a roller manner.

The descriptions of the following embodiments will mainly focus on thepoints that are different from the first embodiment.

Second Embodiment

A second embodiment according to the present invention will be describedas follows in reference to FIG. 4. Here, an identical numeral isassigned to a same element appeared in the first embodiment, and thedetailed description thereof is not presented.

In the first embodiment, the region B being free of groove 2 a providedin the central portion of the polishing pad 2, and the slurry droppingposition is located outside of the region B of the polishing pad 2 beingfree of the groove 2 a. However, in the present embodiment, slurrydropping position is not particularly limited. Since the slurry 8generally moves from the inner side of the polishing pad 2 toward theouter portion by the centrifugal force and cannot move toward the innerdirection, the slurry feeder 7 extends to the interior of the region Bbeing free of groove 2 a as shown in FIG. 4, and even if theconfiguration, in which the slurry 8 is dropped in the region B, isemployed, the slurry 8 cannot remain in the region B being free ofgroove 2 a, and immediately moves into the region A having grooves 2 aformed thereon by a centrifugal force. As a result, the presentembodiment can provide the advantageous effect that is substantiallysimilar to that obtained in the first embodiment. Further, as describedabove, since the wafer 3 rotates and oscillates, the portion contactingwith the region B being free of groove 2 a is not exactly defined, andsome deviation of the slurry dropping position may be permitted as thetarget thereof is to generally provide a uniform polishing rate.

Third Embodiment

A third embodiment according to the present invention will be describedas follows in reference to FIG. 5. Here, an identical numeral isassigned to a same element appeared in the first and the secondembodiments, and the detailed description thereof is not presented.

In the first embodiment, the region B being free of groove 2 a isprovided in the central portion of the polishing pad 2. On the otherhand, grooves 2 a are formed over the entire surface of the polishingpad in the present embodiment. However, the slurry dropping position isdisposed at a position outer from the central portion by a predetermineddistance similarly as in the first embodiment, or in other words, at aposition outer than the region that is desirable to have reducedpolishing rate. Even if the grooves 2 a exist in the central portion ofthe wafer 3, the slurry 8 moves from the inner side of the polishing pad2 to the outer side thereof by a centrifugal force, and cannot movetoward the inner side. Therefore, even if grooves 2 a exist thereon inthe location closer to the center than the slurry dropping position,substantially no slurry 8 moves into the grooves 2 a. As a result, thepresent embodiment can provide the advantageous effect that issubstantially similar to that obtained in the first and the secondembodiments. Since the uniform polishing rate can be provided in thepresent embodiment by employing the polishing pad 2 having theconformation, which is different from that of the first embodiment, itcan be speculated that the present invention can be applied to thepolishing pad 2 of various conformations.

Fourth Embodiment

A fourth embodiment according to the present invention will be describedas follows in reference to FIG. 6. Here, an identical numeral isassigned to a same element appeared in the first to the thirdembodiments, and the detailed description thereof is not presented.

In the first embodiment, the region B being free of groove 2 a isprovided in the central portion of the polishing pad 2. On the otherhand, in the present embodiment, the region B being free of groove 2 ais provided in the circumference portion of the polishing pad 2 a, andthe region A having grooves 2 a formed thereon is provided in the innerportion (central portion) thereof. Then, the retainer ring 4 a and thewafer 3 are disposed so that a portion of the circumference portion ofthe wafer 3, that is, the portion that provides higher polishing ratearound the retainer ring 4 a, (for example, toroidal region having awidth of about 10 mm from the circumference edge), faces against theregion B being free of groove 2 a of the circumference portion of thecircular polishing pad 2, and then the polishing operation is conducted.The retainer ring 4 a and the wafer 3 are reciprocating and oscillatingto continue to relatively move the wafer 3 against the polishing pad 2,and it is preferable that the circumference portion of the wafer 3 (forexample, toroidal region having a width of about 10 mm from thecircumference edge) is in contact with the region B of free of groove,as described above, as taking an average during the polishing operation.Since the groove 2 a that functions as a transfer path for the slurry 8is not formed thereon, substantially no slurry 8 moves to the region B,and thus the polishing rate is lower. Therefore, the present embodimentcan provide the advantageous effect that is similar to that obtained inthe first to the third embodiments.

While the first to the fourth embodiments described above is presentedin consideration of the tendency of providing higher polishing rate inthe circumference portion of the wafer 3 (for example, toroidal regionhaving a width of about 10 mm from the circumference edge of the wafer),the present invention is not limited thereto. More specifically, thepresent embodiment can also be applied even in the case of causing aphenomenon that the polishing rate in the other region of the wafer 3 ispartially increased. The possible cause for partially increasing thepolishing rate, of course, is not limited to the floating (bouncing) ofthe polishing pad 2 around the retainer ring 4 a. Then, a suitableconfiguration may be arbitrarily selected according to the locations ofpartially increasing the polishing rate of the wafer 3, from a groupconsisting of: (i) the configuration of providing the region forproviding lower polishing rate in the central portion of the polishingpad 2 as in the first to the third embodiments; and (ii) theconfiguration of providing the region for providing lower polishing ratein the circumference portion of the polishing pad 2 as in the fourthembodiment.

In addition, while the grooves 2 a are concentric circular in theaforementioned first to fourth embodiments, the geometry of the grooves2 a is not limited to a particular geometry. The grooves 2 a may beformed to have arbitrary geometry such as grid-shape, spiral-shape orthe like Further, while the polishing pad 2 is provided with the regionB being free of groove 2 a in the aforementioned first, second andfourth embodiments, a few grooves 2 a may be formed in this region toprovide lower density thereof, as long as the slurry feed is limited sothat the polishing rate thereof is lower than the other region A.

For example, as shown in FIG. 7 and FIG. 8, polishing can be conductedsimilarly as in the first embodiment except that the region A′ havinggrooves 2 a formed thereon at higher groove density and the region B′having grooves 2 a formed thereon at lower groove density are utilized,to obtain similar advantageous effect. In this case, the outer shape ofeach of the regions A, A′, B and B′ is not necessarily circular.Although the description and the figures contained here illustrate forthe convenience that the region A′ having grooves 2 a formed thereonwith higher density and the region B′ having grooves 2 a formed thereonwith lower density are clearly defined long the radial direction of thecircular polishing pad 2, alternative configuration may also beprovided, in which the density of the grooves 2 a continuously changesalong the radial direction of the polishing pad 2 and thus the entirepad surface can not simply be divided into the region A′ of higherdensity and the region B′ of lower density.

Alternatively, a configuration of having the region A″ having widerwidth of the concave portion of the grooves 2 a formed thereon and theregion B″ having narrower width of the concave portion of the grooves 2a formed thereon in the polishing pad 2 may be employed. For example, asshown in FIG. 9A and FIG. 9B, a configuration of providing the region B″having narrower width of the concave portion of the grooves 2 a in thecentral portion of polishing pad 2 and providing the region A″ havingwider width of the concave portion of the grooves 2 a in thecircumference portion of polishing pad 2 may be employed. In this case,relatively larger quantity of the slurry 8 is supplied to the region A″having wider width of the concave portion of the grooves 2 a and smallerquantity of the slurry 8 is supplied to the region B″ having narrowerwidth of the concave portion of the grooves 2 a. Polishing process isconducted similarly as in the first embodiment except that theabove-mentioned distribution of the slurry 8 based on the difference ofthe width of the concave portion is utilized to obtain similar effectthereto. Of course, an outer shape of each of the regions A″ and B″ arenot necessary to be circular, and the grooves 2 a are not limited tohave a concentric circular geometry. Although the description and thefigures contained here illustrate a configuration for the convenience,in which the region A″ having wider width of the concave portion of thegrooves 2 a and the region B″ having narrower width of the concaveportion of the grooves 2 a are clearly distinguished, alternativeconfiguration may also be provided, in which width of the concaveportion of the grooves 2 a continuously changes and thus the entire padsurface can not simply be divided into region A″ of wider width andnarrower region B″ of narrower width.

Fifth Embodiment

A fifth embodiment according to the present invention will be describedas follows in reference to FIG. 10A, FIG. 10B, FIG. 11 and FIG. 12.Here, an identical numeral is assigned to a same element appeared in thefirst to the fourth embodiments, and the detailed description thereof isnot presented.

As described above, the first to the fourth embodiments involve reducingthe polishing rate of the circumference portion of the wafer 3 bypolishing under the condition of having substantially no slurry 8, andthereby eventually providing the uniform polishing rate. On thecontrary, the present embodiment partially prevents floating (bouncing)of the polishing pad caused by the retainer ring being in compressiblecontact with the polishing pad, as shown in FIG. 15B.

The present embodiment will be specifically described. The grooves 2 aare formed over the entire surface of the polishing pad 2 similarly asin the second embodiment. As shown in FIG. 10A, FIG. 10B and FIG. 11,the circumference portion of the wafer 3 is located in the outercircumference edge portion of the polishing pad 2, and a condition inwhich the retainer ring 4 a extends partially beyond the polishing pad 2is obtained. As shown in FIG. 12, the circumference portion of the wafer3 is sustained by the retainer ring 4 a, and the retainer ring 4 a isdisposed so as to partially extend beyond an edge of the polishing pad 2(step S5). Maintaining such condition, similarly as in each of theaforementioned embodiments, the wafer 3 is in compressible contact withthe polishing pad 2 (step S2), and the polishing pad 2 is rotated andthe wafer 3 is simultaneously rotated (step S3). Then, the slurry 8 isdropped on the polishing pad 2 (step S4) to conduct the polishingoperation.

In such occasion, floating (bouncing) of the polishing pad 2 in theportion of the retainer ring 4 a that extends beyond the edge of thepolishing pad 2 is controlled to be smaller than the conventional, asshown in FIG. 11, thereby preventing an increase of the polishing rate.Of course, it is not always in the situation that the same place of theretainer ring 4 a extend beyond the edge of the polishing pad 2 toreduce the polishing rate, since the retainer ring 4 a continues torelatively move against the polishing pad 2 by rotating, reciprocatingand oscillating the retainer ring 4 a and the wafer 3. Nevertheless,after conducting the polishing operation for one piece of the wafer 3for about 30 seconds to 3 minutes, the polishing rate in thecircumference portion of the wafer 3 adjacent to the retainer ring 4 ais, in general, reduced to a level substantially equivalent to that inthe central portion. Eventually, similarly as in the embodiment shown inFIG. 3, the polishing rate in the circumference portion can be reducedto a level of about ±5% of the polishing rate in the central portion.For example, when the polishing rate in the central portion is 200mm/min, the polishing rate in the circumference portion is about 190 to210 mm/min. In this way, according to the present embodiment, uniformpolishing rate over the wafer 3 is provided, and the flatness thereofis, in turn, improved, similarly as in the first to fourth embodiments.

While the present embodiment employs the polishing apparatus having thebasic configuration that is same as the conventional apparatus includingthe polishing pad, only the location of the carrier 4 is changed toprovide uniform polishing rate.

Method for Manufacturing Semiconductor Device

Next, a exemplary method for manufacturing a semiconductor device byutilizing the wafer polishing method using the polishing apparatusdescribed in the above embodiments will be described in reference toFIGS. 13A to 13F and FIGS. 14A to 14D.

First of all, as shown in FIG. 13A, trenches are formed using a knownlithography technology on a substrate (wafer body) 11 composed ofsilicon or the like (first processing step), and an oxide film 12 isformed on the surface of the substrate 11 having trenches formed thereon(first deposition step). Then, this surface is polished by using thepolishing method illustrated in the aforementioned first to fifthembodiments (first polishing step) to form a shallow trench isolation(STI) 13, which is a trench-type device isolation portion, as shown inFIG. 13B. Subsequently, a well 14, a source region 15 and a drain region16 are formed in a portion sandwiched by a pair of the STIs 13 of thesubstrate by utilizing a known ion implantation technology and alithography technology, as shown in FIG. 13C, and further, a gateelectrode 17 is formed on the surface to compose a transistor (creatingstep). Then, a boro-phospho silicate glass (BPSG) film 18 is depositedthereon (second deposition step).

After that, as shown in FIG. 13D, the aforementioned polishing method isconducted to planarize the surface of the BPSG film 18 (second polishingstep). As shown in FIG. 13E, contact holes are formed in the BPSG film18 by utilizing a known lithography technology (second processing step),and a tungsten film 19 is deposited to cover the BPSG film 18 and fillthe contact holes (third deposition step). Then, the polishing method ofthe above-mentioned embodiments is conducted to remove the tungsten film19 from the surface of the BPSG film 18, while leaving a portion oftungsten in the contact holes, as shown in FIG. 13F (third polishingstep). As such, contacts 19 a, that are coupled to the source region 15,the drain region 16, and the gate electrode 17, respectively, areexposed to the outside.

Thereafter, a known lithography technology is utilized to form aninterlayer insulating film 20 as shown in FIG. 14A (fourth depositionstep), and a trench is formed in the interlayer insulating film 20(third processing step), and then barrier layers 21 and metalinterconnection films 22 are deposited (fifth and sixth depositionsteps). Then, as shown in FIG. 14B, the polishing method of theaforementioned embodiments is conducted to polish the metalinterconnection films 22 and the barrier layers 21 (fourth polishingstep). Further, as shown in FIG. 14C to FIG. 14D, an insulating film 23is formed (seventh deposition step), and a polishing method of theabove-mentioned embodiments is conducted to planarize thereof (fifthpolishing step). As such, the semiconductor device is manufactured. Inaddition, thereafter, a known lithography technology and a knowndeposition technology and the polishing method of the above-mentionedembodiments may be utilized to repeat the formation of the interconnectlayers and the vias.

The semiconductor device can be manufactured with higher accuracy whenthe all polishing processes are carried out by the polishing method ofthe above-mentioned embodiments. Nevertheless, an advantageous effectcan also be obtained when at least one of the polishing process isconducted by utilizing the polishing the method of the above describedembodiments. Here, each of the processes except the polishing processesmay be conducted via conventionally known methods, and since thematerials and configurations for each of the layers of the semiconductordevices are known, detailed description thereof is not presented.Further, each of the aforementioned processes may be appropriatelyomitted and/or may be modified.

It is apparent that the present invention is not limited to the aboveembodiment that may be modified and changed without departing from thescope and spirit of the invention.

1. A method for polishing a workpiece, comprising: providing acompressible contact between a principal surface of a polishing pad anda polishing surface of a workpiece; continuously moving a relativeposition of said polishing pad with said workpiece while the conditionof being in compressible contact between said principal surface of saidpolishing pad and said polishing surface of said workpiece ismaintained; and supplying an abrasive material between said polishingpad and said workpiece, wherein quantity of said abrasive materialcontacting said workpiece has a distribution profile over a region wherethe principal surface of said polishing pad is in contact with thepolishing surface of said workpiece.
 2. The method according to claim 1,wherein said abrasive material has a distribution profile over saidpolishing pad.
 3. The method according to claim 2, wherein saidpolishing pad is rotated around a central axis, and said workpiece isoscillated on a region where said abrasive material has a distributionprofile.
 4. The method according to claim 3, wherein, on said polishingpad, quantity of said abrasive material is lower in a location that iscloser to the center than a position where said abrasive material isdropped, and quantity of said abrasive material is higher in a locationthat is closer to the outer circumference than said position.
 5. Themethod according to claim 3, wherein said polishing pad is provided withgrooves formed thereon, and wherein, on said polishing pad, quantity ofsaid abrasive material is lower in a region where density of saidgrooves is lower, and quantity of said abrasive material is higher in aregion where density of said grooves is higher.
 6. The method accordingto claim 5, wherein density of said grooves is lower in a central regionof said polishing pad, and density of said grooves is higher in acircumference region thereof.
 7. The method according to claim 5,wherein said central region of said polishing pad is free of saidgroove.
 8. The method according to claim 3, wherein said polishing padis provided with grooves formed therein, and wherein, on said polishingpad, quantity of said abrasive material is lower in a region where awidth of a concave portion in said groove is narrower, and quantity ofsaid abrasive material is higher in a region where a width of a concaveportion in said groove is wider.
 9. The method according to claim 8,wherein a width of a concave portion in said groove is narrower in acentral region of said polishing pad, and a width of a concave portionin said groove is wider in a circumference region of said polishing pad.10. The method according to claim 1, further comprising: providing acompressible contact between a principal surface of said polishing padand a polishing surface of said workpiece, so that at least a portion onthe polishing surface of said workpiece, which tends to provide higherpolishing rate, is located in a region on the principal surface of saidpolishing pad, which contains less quantity of said abrasive material.11. The method according to claim 10, wherein a ring-type retainersurrounds a circumference portion of said workpiece to sustain saidworkpiece, and wherein said portion on the polishing surface of saidworkpiece, which tends to provide higher polishing rate, is a portion ofsaid circumference portion being adjacent to said ring-type retainer.12. A method of polishing a workpiece, comprising: providing acompressible contact between a principal surface of a polishing pad anda polishing surface of a workpiece; continuously moving a relativeposition of said polishing pad against said workpiece while thecondition of being in compressible contact between said principalsurface of said polishing pad and said polishing surface of saidworkpiece is maintained; and supplying an abrasive material between saidpolishing pad and said workpiece, wherein a circumference portion ofsaid workpiece is sustained with a ring-type retainer, and wherein saidpolishing pad is in compressible contact with said workpiece, while saidring-type retainer is disposed so that at least a portion of saidring-type retainer extends beyond an edge of said polishing pad.
 13. Apolishing pad for polishing a workpiece by forcing a rotating workpieceto provide a compressible contact between said workpiece and saidpolishing pad and by supplying abrasive material between said workpieceand said polishing pad while said polishing pad being rotated, whereinsaid polishing pad is partially provided with grooves formed therein,and wherein density of said grooves has a distribution profile across aprincipal surface of said polishing pad, thereby said polishing padbeing provided with a first region having lower polishing rate and asecond region having higher polishing rate.
 14. The polishing padaccording to claim 13, wherein the density of said groove on saidpolishing pad is lower in a region of said polishing pad correspondingto higher polishing rate portion of said workpiece and the density ofsaid groove on said polishing pad is higher in a region of saidpolishing pad corresponding to lower polishing rate portion of saidworkpiece.
 15. The polishing pad according to claim 13, wherein a widthof a concave portion in said groove of said polishing pad is narrower ina region of said polishing pad corresponding to higher polishing rateportion of said workpiece and a width of a concave portion in saidgroove of said polishing pad is wider in a region of said polishing padproviding lower polishing rate portion of said workpiece.
 16. Thepolishing pad according to claim 13, wherein the density of said groovesis lower in a central region of said polishing pad.
 17. The polishingpad according to claim 13, wherein the width of the concave portion insaid groove is narrower in a central region of said polishing pad. 18.The polishing pad according to claim 13, wherein the central region ofsaid polishing pad is free of said groove.
 19. The polishing padaccording to claim 13, wherein said grooves are concentric circular. 20.A polishing apparatus comprising the polishing pad according to claim13.
 21. The polishing apparatus according to claim 20, furthercomprising: a polishing pad driving unit which rotates said polishingpad; an abrasive material feeding unit which supplies an abrasivematerial to a predetermined position on said polishing pad; and aworkpiece driving unit which rotates said workpiece while forcing saidworkpiece so that said workpiece is in compressible contact with saidpolishing pad.
 22. The polishing apparatus according to claim 21,wherein said polishing pad driving unit and said workpiece driving unitcomprise a mechanism for providing provides a compressible contactbetween a principal surface of said polishing pad and a polishingsurface of said workpiece so that at least a portion of the polishingsurface of said workpiece having tendency to provide higher polishingrate is located in a region containing smaller amount of said abrasivematerial of a principal surface of said polishing pad.
 23. The polishingapparatus according to claim 22, wherein said workpiece driving unitcomprises a ring-type retainer for surrounding a circumference portionof said workpiece to sustain said workpiece, and wherein said portion ofthe polishing surface of said workpiece having tendency to providehigher polishing rate is a portion of a circumference portion beingadjacent to said ring-type retainer.
 24. A polishing apparatus,comprising: a polishing pad; a polishing pad driving unit which rotatessaid polishing pad; and a workpiece driving unit which forces saidworkpiece so that said workpiece compressibly contacts said polishingpad while rotating said workpiece, said workpiece driving unitcomprising a ring-type retainer for surrounding a circumference portionof said workpiece to sustain said workpiece, and said workpiece drivingunit being capable of sustaining said workpiece thereon so that at leasta portion of said ring-type retainer extends beyond an edge of saidpolishing pad.
 25. A method for manufacturing a semiconductor device,comprising: creating a conducting region within a wafer by utilizing anion implantation technology; forming an insulating layer and/or aconducting layer by utilizing a deposition technology, both of saidlayers composing a portion of said wafer; processing said wafer into apredetermined shape by utilizing a lithography technology; andrecognizing said wafer as a workpiece and conducting the method forpolishing the workpiece according to claims
 1. 26. A method formanufacturing a semiconductor device, comprising: forming an insulatingfilm on the semiconductor substrate; and polishing a surface of saidinsulating film to planarize the surface of said insulating film,wherein said polishing is conducted by utilizing said method forpolishing the workpiece according to claims
 1. 27. A method formanufacturing a semiconductor device, comprising: forming an insulatingfilm on the semiconductor substrate; forming a groove on said insulatingfilm; forming a conducting film within said groove and on saidinsulating film; and polishing at least a portion of said conductingfilm formed on said insulating film to planarizing a surface composed ofthe surface of said insulating film and the surface of said conductingfilm, wherein said polishing is conducted by utilizing said method forpolishing the workpiece according to claims 1.